A weekly at-home treatment, not a conditioner, that reduces breakage and visibly strengthens hair, improving its look and feel. Clients can benefit from this global bestseller whether or not they receive chemical services. Use No.0 as the first step in a two-part at-home system with No.3 Hair Perfector to strengthen and repair all types of damaged hair. Apply a generous amount from roots to ends on damp, towel dried hair. Comb through once and leave on for a minimum of 10 minutes or more. Rinse from hair, shampoo, and condition.